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- <CFSET Title = "DCP Concepts">
- <CFINCLUDE TEMPLATE="_header.cfm">
-
- <h3>DCP Concepts</h3>
- <h4>Objects, Classes, and Content</h4>
- <P>The content publishing model in this example application is based on the idea
- of <I>objects</I>. An object is a piece of information or a group of related
- information. For example, the title of a press release, an executive summary
- of the press release, the body of the press release, and a Word document of
- the press release would all be pieces of content contained in the same Press
- Release object.</P>
- <P>Depending on the way the object is called, the content can be displayed in
- different ways. A News Summary page might only display titles of news objects,
- but clicking on one of those titles could call a page which shows all of the
- content of the object.</P>
- <P>Each object must be of a certain <I>class</I>, such as News Items and Press
- Releases. The class of an object allows pages to determine how objects should
- be formatted when they are displayed.</P>
- <P>So far, each <I>object</I> has pieces of <I>content</I>, and every <I>object</I>
- belongs in a certain <I>class</I>. Each piece of content also has a <I>content
- type</I>, such as Headline, Teaser (executive summary), Body, File, Image, etc.
- As with object classes, content types allow pages to determine how content should
- be formatted when they are displayed.</P>
- <P>Not all content types are allowed for all object classes; for example, all
- News Items are required to contain a Headline, Teaser, and Body; they may optionally
- contain a File, Image, or Hyperlink to be displayed along with the image; and
- they may not contain an Address or Phone Number. These relationships are defined
- in the database table PubClassDefinitions.</P>
- <h4>Implicit/Explicit Calls, Instances, and Pages</h4>
- <P>There are two ways in which objects can be displayed. The first way is through
- an <i>explicit call</i>; i.e., a page contains code that says "Display the object
- with ObjectID 23 here." The second way is through an <i>implicit call</i>; the
- page says "See if any objects are supposed to be displayed on this page, in
- this spot, at this time; if so, display them in the proper order."</P>
- <P>The way objects respond to implicit calls is through <I>instances</I>. If the
- user wants object 23 to appear on three different pages in the web site, three
- separate instances must be created.</P>
- <P>In order for instances to be scheduled for a page, that page must be registered
- with the system, and given its own PageID. Then, when the page is called, it
- finds the instances that match its PageID (and other criteria) and displays
- the objects associated with each instance.</P>
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- <CFSET HREF="3-under1.cfm">
- <CFSET Link="Under the Hood, Pt. 1">
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